Method and apparatus for adjustably induced biaxial strain

Abstract

An apparatus comprising a shape memory alloy is configured as a ring shaped sample holder for a transmission electron microscope and imparts uniform biaxial strain on a thin film mounted within. The sample holder responds to a change in temperature by changing the inner diameter, which imparts biaxial strain. In other embodiments, the sample holder is configured to change the inner diameter and change the strain on a thin film reversibly and repeatedly. In further embodiments, the sample holder is non circular. In still further embodiments, the apparatus is configured as a prime mover of a reversible radial actuator. Methods for making and using the apparatus are included in other embodiments.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority from U.S. provisional application Ser. No. 60 / 467,163 filed on Apr. 30, 2003, incorporated herein by reference in its entirety.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT[0002]This invention was made with Government support under Grant No. DE-AC03-76SF00098, awarded by the Department of Energy. The Government has certain rights in this invention.INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC[0003]Not ApplicableNOTICE OF MATERIAL SUBJECT TO COPYRIGHT PROTECTION[0004]A portion of the material in this patent document is subject to copyright protection under the copyright laws of the United States and of other countries. The owner of the copyright rights has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the United States Patent and Trademark Office publicly available file or records, but otherwise r...

AI Technical Summary

Benefits of technology

The present invention relates to an apparatus and method for making and using a sample holder that will induce biaxial strain on a thin film in response to temperature changes. The sample holder is made of a shape memory alloy, such as NiTi, which will return to its original shape when heated or cooled. The apparatus includes a ring with a first inner perimeter and a second inner perimeter that can change in size as a function of temperature. The ring can securely hold a thin film in place and induce biaxial strain on the thin film as the temperature changes. The invention can be used for dynamic microstructural characterization of thin films, such as biological microsensors, microactuators, and data storage devices. The sample holder can also be used as a reversible radial actuator or a reversible radial brake. The invention provides a means for securely holding a thin film and inducing biaxial strain on it.

Problems solved by technology

Such techniques present challenging problems because bulk methods such as uniaxial tension testing, are very difficult to apply directly to films.

Difficulties include generating forces and strains required in a small space, gripping the film, and prevention of bending force components in the film.

While micro-electromechanical uniaxial strain fixtures have been fabricated, the approach does not generate the state of strains and stresses seen in chemical and biological micro-sensors, micro-actuators, passivation layers, micro-electronics, data storage and other film-based devices.

In addition, it is infeasible to install the complex bulge test apparatus inside the five cubic millimeter volume and vacuum environment of a Transmission Electron Microscope (TEM) objective lens.

Inducing radial strain through direct thermal expansion for observation of a thin film by a TEM is infeasible.

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